1. Field of the Invention
The invention provides nucleotide sequences from Coryneform bacteria which code for the luxR gene and a process for the fermentative preparation of amino acids, in particular L-lysine by attenuation of the luxR gene. The luxR gene codes for the LuxR protein, which is a transcription activator.
2. Discussion of the Background
L-amino acids, particularly L-lysine, are used in human medicine and in the pharmaceuticals industry, in the foodstuffs industry and, most particularly, in the feeding of animals.
It is known that amino acids are produced by fermentation of strains of Coryneform bacteria, in particular Corynebacterium glutamicum. Because of their great importance, attempts are continuously being made to improve the production processes. Improvements to the processes may concern measures relating to the fermentation, such as, for example, stirring and oxygen supply, or the composition of the nutrient media, such as, the sugar concentration during the fermentation, or working up to the product form by, for example, ion-exchange chromatography, or the intrinsic performance properties of the microorganism itself.
In order to improve the performance properties of such microorganisms, methods of mutagenesis, selection and mutant selection are employed. Such methods yield strains which are resistant to antimetabolites or are auxotrophic for metabolites that are important in terms of regulation, and which produce amino acids.
For a number of years, methods of recombinant DNA technology have also been used for improving the strain of L-amino acid-producing strains of Corynebacterium. However, there remains a critical need for improved methods of producing L-amino acids and thus for the provision of strains of bacteria producing higher amounts of L-amino acids. On a commercial or industrial scale even small improvements in the yield of L-amino acids, or the efficiency of their production, are economically significant. Prior to the present invention, it was not recognized that attenuation of luxR gene encoding the a LuxR transcriptional activator protein would improve L-amino acid yields.